| 摘要 |
PURPOSE:To decrease the number of lines at a center side by sending a signal to show the communication speed of MODEM from a slave station to the center before communication is started and selecting the MODEM corresponding to the communication speed at the center. CONSTITUTION:When a slave station 1 executes the calling, the number of a line 5 of a center 4 is dialed by a network control unit NCU11 of the slave station 1. At the center 4, an NCU 41 closes a line. When the line is closed, a MODEM 12 of the slave station l transmits an MF signal that a communication speed is 1200 bps, to the center 4. The center 4 gives an instruction to a change-over switch 49 and connects a 1200 bps MODEM 42 to the line. In the same way, when calling is executed from a slave station 2 and a slave station 3, in respective cases, a MODEM 44 of 2400 bps and a MODEM 4800 bps are selected by the change-over switch 49 and the communication is executed between the slave stations 2 and 3 and the center 4.
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